In the context of minimally invasive medicine the endeavor is to carry out an operation which causes the minimum degree of trauma to the patient. In that respect the endeavor is to gain access to the depth of the tissue either by way of the natural body openings of the patient as in the case of interventional endoscopy by way of instruments (endoscope) with visual control or however by way of small incisions directly at the location of intervention, in order there to remove tissue for diagnostic purposes, for example for histological tissue determination or for therapy purposes, for example for tumor removal.
In recent years the development of suitable instruments for minimally invasive surgery has been the subject of rapid progress as that operating technique affords considerably advantages for cosmetic reasons, for minimizing post-operative complications and for speeding up the healing process.
Apparatuses are known by the name “Fine needle aspiration” (FNA) or “true cut needle biopsy”, which have a fine needle which is introduced into a suspicious area of tissue and by means of which one or more tissue samples can be removed purely mechanically by way of a cutting or perforating mechanism in order to subject that tissue to histological examination.
Thereafter possibly in the event of malignant findings suitable surgical measures can be initiated. The volumes of tissue which can be removed with those needle probes however are only very small and are therefore suitable exclusively for diagnostic purposes. By virtue of the small volume of tissue which can be removed in one puncture insertion a plurality of puncture insertions into the suspicious area of tissue are therefore often required, which under some circumstances can result in spreading of malignant tumor cells. In addition the degrees of accuracy of the histological tissue results are not optimum, by virtue of the small volume of tissue involved.
U.S. Pat. Nos. 5,775,333 and 5,782,795 disclose surgical instruments which permit larger volumes of tissue to be removed by virtue of multiple tissue removal from the same target area. Those known instruments use a vacuum-supported mechanical punching-cutting device which reduces the number of puncture insertions required and which in addition also improves the level of accuracy of the diagnostic findings, by virtue of the larger volume of tissue. It is also often possible with those known instruments for relatively small changes in tissue to be already removed in toto, which under some circumstances makes a subsequent operation unnecessary.
In the case of the instrument in accordance with U.S. Pat. No. 5,775,333 a needle-shaped hollow probe is introduced into the target area, for example a breast tumor. Disposed laterally at the end of the probe is an elongate opening into which the tissue to be removed is sucked. Disposed within the apparatus is a rotating hollow blade which by the way of a mechanical advance cuts off the tissue which has been sucked into the opening, within the apparatus, and sucks it away through the hollow probe by means of a vacuum. By successive rotation of the shaft through 360° a given volume of tissue which has been previously sucked into the hollow probe and cut away is removed around the distal end of the probe, which however is often not entirely sufficient for complete removal of the medically suspicious area of tissue.
U.S. Pat. No. 5,817,034 discloses a surgical instrument in which a tubular cylindrical blade of a diameter of up to 25 mm is advanced as far as the target area. The head portion of the cylinder which is thus punched out within the apparatus is severed by way of a loop which is disposed at the end and which is subjected to the action of HF-voltage, and then the entire severed cylinder of tissue is removed by way of the apparatus. Admittedly that known system can provide that the suspicious area of tissue can be removed in toto, but also a great deal of healthy tissue is removed, until the tip of the probe has reached the suspicious area of tissue, and a relatively large scar is then left behind by virtue of the large diameter of the apparatus.
U.S. Pat. No. 5,810,806 discloses a surgical probe in which the tissue is not cut into by means of a mechanical annular blade but by means of an axially immovable loop which is fixed at the distal end of the hollow body and which is supplied with an HF-voltage and thereby acts as a cutting blade. In a cutting operation the cylinder of tissue which is cut off at the periphery by the HF-loop is displaced frontally into the forwardly open hollow body and then is severed at the end of the procedure by a windshield wiper-like rotary movement of the loop which is subjected to the action of HF-voltage. That known apparatus also provides that the tissue is completely severed only when it is in the hollow body, whereby a great deal of healthy tissue is also removed therewith until the tip of the probe has been advanced as far as the suspicious area of tissue. A further disadvantage is that only the cylinder of tissue in front of the front opening of the hollow body can be removed.
German applications 197 06 751 and 195 28 440 disclose an electrosurgical device of the kind set forth in the opening part of this specification, in which a loop-shaped cutting element is adapted for electrosurgically cutting out tissue in parallel relationship with the longitudinal axis of an elongate hollow body and while retaining that orientation can be moved in a loop shape out of the hollow body so that then the adjoining tissue can be cut out in a toric shape by virtue of rotation of the hollow probe. The tissue which is cut out can then be introduced into the hollow passage of the hollow body through the same opening through the cutting element issues, and can then be transported along the hollow passage to the proximal end of the device. That known device has the advantage that the puncture location is of small dimensions and that it is then possible to take at the treatment location a piece of tissue which surrounds the hollow probe in externally adjoining relationship therewith. A disadvantage in this case however is that the volume of tissue which can be cut out is relatively is small and is therefore not sufficient for thorough examination of even larger regions of tissue.
PCT application WO 99/44506 issued as U.S. Pat. No. 6,331,166, discloses a loop-shaped cutting element which can be moved out of the hollow body in a plane which extends transversely with respect to the longitudinal axis of the hollow body, wherein after the cutting element has been moved out of the hollow body it is displaceable along the hollow body.
U.S. Pat. No. 5,810,659 discloses a surgical probe for removing tissue, in which the distal end of a shaft carries a sharply ground cutting sleeve to which a HF-voltage can be applied. Disposed distally behind the cutting sleeve, at a guide wire extending centrally through the catheter, is a ceramic body as a counterpart support for the cutting sleeve, at the end of which a rounded-off metal electrode is fixed and connected by way of the guide wire to a HF-generator. By way of an operating member, the cylindrical counterpart support can be moved by way of the guide wire to the sharply ground metal sleeve, in which case the tissue disposed therebetween is purely mechanically severed by the sharp ground portion of the metal sleeve and is thus collected within the proximal cutting sleeve. Both the proximal sleeve and also the metal electrode fixed to the counterpart support are connected to an HF-generator and thus permit bipolar coagulation of tissue in order possibly also to stop bleeding. That however does not involve a technical solution for easily removing the biopsate once collected. The tissue has to be removed from the sleeve in a complicated procedure using micro-tweezers or a needle.
PCT published application PCT/US99/21416 now U.S. Pat. No. 6,261,241, discloses a rigid surgical instrument, which also comprises a sleeve configuration displaceable relative to each other in order to remove tissue samples and to coagulate the tissue. The novelty in relation to the state of the art lies on the one hand in the complicated and expensive, partly automated operating member, and in the possibility of applying a cutting current to one of the two displaceable sleeves in order to electrosurgically cut off the tissue. In a further embodiment the cutting operation is not implemented by way of the sleeve itself, but a fixed cutting electrode which is let into the casing at the proximal periphery of the sleeve.